Sunday, May 16, 2021, 00:10
Science and sociology associated with the calendar make it very difficult to put everything behind. We draw attention to the degree of time (chronology). Historically, the basic unit for calculations was the day. The other temporary periods are nothing more than groups of days. The two most common, months and years, together with the days, are based on astronomical periods that, which are immeasurably with each other, introduce complexity in the elaboration of the calendar. The rest, just like the week, is artificial. But chronology does not ensure that the basic unit of time is constant. It does not say whether the duration of the first day in a sequence of days is the same as that of the latter. To verify it, the scientific measure of time (the chronometry) is needed that was dependent on astronomers until lately. In any case, The proof of time from astronomical size has still not been resolved. That is why it is impossible to compare units from the past, for example seconds with later seconds.
Until the first third of the twentieth century, the time of time was the day: the period of rotation of the earth on its axis. It was measured by astronomers who took the sun, sun day or, in other cases, some regular stars, Sidereal day. The latter were defined as the 1/86400 group of the day. This made it possible to make relationships between the Sidereale Tijd, the apparent (irregular) solar sun and the middle plot. The clocks of the 18th century, more accurate and controlled, had the time between astronomical observations. The use of the day as a basic unit in chronology and chronometry was therefore possible to create a good relationship, although complex, between astronomical measures and calendar. In the mid -nineteenth century, the dynamic theories of the solar system were refined into account the moon and the planets. This yielded important progress in time. But because of the variability of the rotation movement of the earth, it was still inaccurate. In 1950 the tropical or seasonal year was introduced and time was based on the most important Ephemeris of the sun, the moon and the planets, the independent variable of the dynamic comparisons of the planetary movement. The second was again defined as group 1/31556925,9747 of the tropical year.
From 1929 the quartz watches (Oscillator) replaced astronomical observation. This new measure was improved in the 40s with atomic watches and with atomic watches driven by cesiumoscillators. On January 1, 1972, the International Atomic era was determined to define the second of a constant and permanent property of these watches. It turned out that each of the days does not include exactly 86,400 atomic seconds. That is why corrections are needed. For example, occasionally introduce a second to ensure that the afternoon is reached at noon.
